The Chronicle's Zachary Levine, author of "the unofficial scorer" blog, shows us a brief comparison of the Astros' 2008 and 2009 starts to the season. The Astros have followed a remarkably similar W / L path at the beginning of both seasons. The Astros stand at an identical 8-12 record compared to this point last year.
He concludes that the 09 start has been stronger than the 08 start. One could quibble over that conclusion; it just depends on which stats you think are most important. Levine is reassured by the fact that the Astros' batting average and OBP has been better so far this year. He thinks that bodes well for the future, as clutch hitting stats start to even out. On the other hand, the 09 team has shown less power, with lower slugging and home run rates. He also concludes that the pitching is clearly better, mostly based on a significantly improved ERA. I would note that the BB and K rates are worse in 09, which some people would emphasize over the ERA.
I have to think that the improved performances of Pence and Bourn at this point in the season is a significant factor in the OBP upgrade. The Astros are striking out at a higher rate, and I suspect that Berkman's strike out problems to begin the season may be a reason.